The present invention is related to systems and methods for providing differential signaling.
FIG. 1 shows a simplified diagram 100 of differential signaling with a differential signal 110 switching from a high voltage (Vhigh) to a low voltage (Vlow), and another differential signal 120 switching from Vlow to Vhigh. A common mode voltage (Vcm) 130 is also depicted. Common mode voltage is the average of Vhigh and Vlow as set forth in the following equation:Vcm=(Vhigh+Vlow)/2
A number of applications utilize differential signaling. As an example, differential signaling is used for the Universal Serial Bus that is supported by many personal computer manufacturers. In the current 480 Mbps mode operable on the Universal Serial Bus, the common mode voltage may vary from negative fifty mV to six hundred mV, and exhibit a differential signal swing of only four hundred mV. When the Universal Serial Bus was originally developed, semiconductor processes were typically 3.3 volts or higher. At such voltage levels, the common mode variation was often manageable. Currently, however, a typical semiconductor processes are 1.8 volts, and the trend is moving toward lower and lower voltages. At these lower voltages, common mode variation may become significant and unmanageable using known techniques, especially when differential signaling from legacy devices is encountered.
Hence, for at least the aforementioned reasons, there exists a need in the art for advanced systems and methods for performing differential signaling.